Another brilliant piece of work by Joel Schneider. I have been talking about ability domain cohesion for the past decade (http://www.iqscorner.com/search?q=Cohesion)....now Joel has outlined how to deal with the concept psychometrically. Well done.

This looks like another issue that might need the attention of SCOTUS.

The following section is extracted from the complete ruling.

E. Implications of the Flynn Effect

There is good reason to have pause before
retroactively adjusting IQ scores downward to offset the Flynn Effect.
As we noted above, see n.1, supra, the Flynn Effect describes the
apparent rise in IQ scores generated by a given IQ test as time elapses
from the date of that specific test’s standardization. The reported
increase is an average of approximately three points per decade, meaning
that for an IQ test normed in 1995, an individual who took that test in
1995 and scored 100 would be expected to score 103 on that same test if
taken in 2005, and would be expected to score 106 on that same test in
2015. This does not imply that the individual is “gaining intelligence”:
after all, if the same individual, in 2015, took an IQ test that was
normed in 2015, we would expect him to score 100, and we would consider
him to be of the same “average” intelligence that he demonstrated when
he scored 100 on the 1995-normed test in 1995. Rather, the Flynn Effect
implies that the longer a test has been on the market after initially
being normed, the higher (on average) an individual should perform, as
compared with how that individual would perform on a more recently
normed IQ test.

At first glance, of course, the Flynn Effect
is troubling: if scoring 70 on an IQ test in 1995 would have been
sufficient to avoid execution, then why shouldn’t a score of 76 on that
same test administered in 2015 (which would produce a “Flynn-adjusted”
score of 70) likewise suffice to avoid execution? Further, even if IQ
tests were routinely restandardized every year or two to reset the mean
score to 100, and even if old IQ tests were taken off the market so as
to avoid the Flynn Effect “inflation” of scores that is visible when an
IQ test continues to be administered long after its initial
standardization, that would only mask, but not change, the fact that IQ
scores are said to be rising.

Indeed, perhaps the most puzzling aspect of
the Flynn Effect is that it is true. As Dr. Tassé states in his
declaration, “[t]he so-called ‘Flynn Effect’ is NOT a theory. It is a
wellestablished scientific fact that the US population is gaining an
average of 3 full-scale IQ points per decade.” The implications of the
Flynn Effect over a longer period of time are jarring: consider a cohort
of individuals who, in 1917, took an IQ test that was normed in 1917
and received “normal” scores (say, 100, on average). If we could
transport that same cohort of individuals to the present day, we would
expect their average score today on an IQ test normed in 2017—a century
later—to be thirty points lower: 70, making them mentally retarded, on
average.

Alternatively, consider a cohort of
individuals who, in 2017, took an IQ test that was normed in 2017 and
received “normal” scores (of 100, on average). If we could transport
that same cohort of individuals to a century ago, we would expect that
their average score on a test normed in 1917 would be thirty points
higher: 130, making them geniuses, on average.

It thus makes little sense to use
Flynn-adjusted IQ scores to determine whether a criminal is sufficiently
intellectually disabled to be exempt from the death penalty. After all,
if Atkins stands for the proposition that someone with an IQ score of
70 or lower in 2002 (when Atkins was decided) is exempt from the death
penalty, then the use of Flynn-adjusted IQ scores would conceivably lead
to the conclusion that, within the next few decades, almost no one with
borderline or merely below-average IQ scores should be executed,
because their scores when adjusted downward to 2002 levels would be
below 70. Indeed, the Supreme Court did not amplify just what moral or
medical theory led to the highly general language that it used in Atkins
when it prohibited the imposition of a death sentence for criminals who
are “so impaired as to fall within the range of mentally retarded
offenders about whom there is a national consensus,” 536 U.S. at 317. If
Atkins had been a 1917 case, the majority of the population now
living—if we were to apply downward adjustments to their IQ scores to
offset the Flynn Effect from 1917 until now—would be too mentally
retarded to be executed; and until the Supreme Court tells us that it is
committed to making such downward adjustments, we decline to do so.

* * *

COLE, Chief Judge, concurring in the opinion
except for Section II.E. I concur with the majority opinion except as
to the section discussing the implications of the Flynn Effect. In
holding that Black did not prove that he had significantly subaverage
general intellectual functioning, we concluded that Black’s childhood IQ
scores would be above 70 even if we adjusted those scores to account
for both the SEM and the Flynn Effect. Accordingly, I would not address
the question of whether we should apply a Flynn Effect adjustment in
cases generally because it is unnecessary to the resolution of Black’s
appeal. Regardless, courts, including our own in Black I, have regarded
the Flynn Effect as an important consideration in determining who
qualifies as intellectually disabled. See, e.g., Black v. Bell, 664 F.3d
81, 95–96 (6th Cir. 2011); Walker v. True, 399 F.3d 315, 322–23 (4th
Cir. 2005).

About Me

Dr. Kevin McGrew is Director of the Institute for Applied Psychometrics (llc). Additional information, including potential conflicts of interest resulting from commercial test development or other consultation, can be found at The MindHub(TM; http://www.themindhub.com ). General email contact is iap@earthlink.net.